The present invention relates to a method of controlling a lens stop position in an electrophotographic copying apparatus with a magnification changing function.
Generally, an electrophotographic copying apparatus having a magnification changing function, particularly, an electrophotographic copying apparatus with a stepless magnification changing function having a zoom lens mounted thereon employs a stepping motor for driving the lens. In addition, in such an electrophotographic copying apparatus as referred to above, a home position is set in the extent of the movement of the lens, and therefore, the lens is arranged to be moved centering on the home position. However, if electrical disturbances from outside such as noises, etc. are given rise to, or dust and/or toner are present in a driving part of the copying apparatus during the movement of the lens, it may happen that the lens does not stop exactly at a desired position. Moreover, the stop position may possibly be missed when a discordance phenomenon is caused, that is, toning is lost while the stepping motor is being driven.